Biomass determination based on the individual volume of the dominant copepod species in the Western Egyptian Mediterranean Coast

Abstract

The biomass of five copepod species (Oithona nana, Calocalanus pavo, Nannocalanus minor, Clausocalanus arcuicornis and Paracalanus parvus) that dominate the western part of the Egyptian Mediterranean Coast had been determined using the individual volume. The length-weight relationships and physicochemical influences on the length of species were also investigated. Copepod samples were seasonally collected during the period 2008–2009. All volumes and weights of the randomly selected adult individuals were measured. Ten regression equations confirmed that; the species weights depend on the total lengths of males and females of all species. However, the females of the examined species were always heavier and longer than males. The length and weight of both sexes of all species were higher in winter than in other seasons. Temperature is considered the main factor influencing the sizes of adult copepods. It was also found that the mean length of the examined individuals was inversely proportional to temperature. However, all the investigated organisms had adequate high levels of dissolved oxygen and didn't show any change with pH, salinity and transparency.